Known brand names include Trandate.
A beta blocker that also blocks alpha receptors, so it relaxes blood vessels and keeps the heart from speeding up. Tablets treat high blood pressure, and the IV form is given for severe high blood pressure.
Labeled use. Tablets for hypertension, alone or with diuretics; IV injection and infusion for severe hypertension.
IV labetalol is a first-line choice for acute severe hypertension in pregnancy and preeclampsia, alongside IV hydralazine and oral nifedipine, and oral labetalol is widely used for chronic hypertension in pregnancy; pregnancy is not a separately labeled indication. Its combined alpha and beta blockade lowers pressure without reflex tachycardia, which makes it a common IV choice in hypertensive emergencies. Avoid it in asthma, COPD, bradycardia, heart block, and decompensated heart failure, where hydralazine or a calcium channel blocker may fit better. It is not a first choice for uncomplicated primary hypertension.
Combines selective, competitive alpha-1 blockade with nonselective, competitive beta blockade; the alpha-to-beta ratio is about 1:3 orally and 1:7 IV. Blood pressure falls in a dose-related way through lower peripheral resistance, without reflex tachycardia and with only a small drop in resting heart rate. Because of the alpha-1 blockade, pressure falls more standing than supine. Oral doses peak at 2 to 4 hours; each IV dose reaches maximal effect within 5 minutes.
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The labels do not describe a narrow therapeutic index or direct dosing by measured blood levels of the drug.
Doses come from the FDA label. Study tool, not for clinical decisions.
No labeled dose change. Half-life is not altered in renal impairment, and dialysis removes less than 1%. IV use can transiently raise BUN and creatinine, mainly in patients with prior renal insufficiency.
None on the current tablet or injection labels. Abrupt cessation is a labeled warning instead.
No specific antidote. Overdose causes posture-sensitive hypotension and sometimes marked bradycardia: lay the patient flat, raise the legs if needed, and give supportive care. Shortly after an oral overdose, gastric lavage may help remove the drug. Hemodialysis and peritoneal dialysis remove less than 1%.
Extensive published experience has not shown a drug-linked rise in major birth defects, miscarriage, or poor outcomes for mother or fetus, though most data involve IV labetalol after 20 weeks and the studies have limits. Labetalol crosses the placenta, so newborns may have hypotension, bradycardia, hypoglycemia, or respiratory depression and should be monitored. Untreated hypertension in pregnancy raises the risk of preeclampsia, preterm delivery, fetal growth restriction, and fetal death.
Published data find low levels of labetalol in breast milk. No data describe effects in the breastfed infant or on milk production, so weigh the benefits of breastfeeding against the mother's need for the drug.
Safety and effectiveness in children have not been established for the tablets or the injection. Beta blockers raise the risk of severe or prolonged hypoglycemia, especially in children.